Ischemic heart disease is a significant clinical problem and results obtained during the previous grant period show that increased expression of specific heat shock proteins (HSP) exerts a protective effect against ischemia-reperfusion (Ism-Reper) induced myocardial injury. Important questions related to the protective effects of HSPs against Ism-Reper induced myocardial injury remain unanswered. We will determine in Aim I if small HSPs, aB-crystallin and HSP27, have a protective effect against Ism-Reper induced injury by themselves, in combination with each other, and with HSP70 family members. Adenoviral vectors expressing the small HSPs aB-crystallin and HSP27 at high levels upon infection of cardiac myocytes have been generated and show a protective effect in preliminary studies. In addition, transgenic mice expressing aB-crystallin and HSP27in their hearts are available for these studies. In Aim II we will determine the basis for protective effects of specific HSPs like the inducible HSP70 (HSP70i), the constitutive HSP70, and the small HSPs aB-crystallin and HSP27 against Ism-Reper induced injury especially cell death by apoptosis and necrosis and decreased myocardial function. Preliminary findings indicate that increased expression of HSP70i hasa protective effect against Ism-Reperinduced apoptosis mediated cell death. Our preliminary findings using confocal microscopy showing that increased expression of small HSPs leadsto protection of specific cytoskeletal structures against ischemia-induced injury will also be further explored. In Aim III, we would like to investigate novel approaches to apply the protective effect of HSPs against Ism-Reper induced injury to the clinical situation. Our very recent findings indicate that 80-90% of myocytes can be infected by adenoviral vectors expressing specific HSPs after perfusion of hearts. Such hearts and myocytes or muscle strips derived from them are used to determine the dose response and time course of protective effects of specific HSPs against Ism-Reper. Results obtained from these investigations of protective effects of specific HSPs against Ism-Reper induced myocardial injury may lead in the future to new treatment strategies for ischemic heartdisease.